Method for the electrolytic production of alkali metals



March 14, 1939.

l. J. MOLTKEHANSVEN METHOD FOR THE ELECTROLYTIC PRODUCTION OF ALKALI METALS 2 Sheets-Shae Filed Oct. 25, 1954 rlllllll lllll llll March 39- l. J. MOLTKEHANSEN METHOD FOR THE ELECTROLYTIC PRODUCTION OF ALKALI METALS Filed 001;. 25, 1934 2 Sheets-Sheet 2 Patented Mar. l4, 1939 ass, for electrolysing sodium nitrate in order to- PATENT OFFICE METHOD FOR THE -ELECTROLYTIC PRO- DUCTION.OF ALKALI METALS i Ivar Juel Moltkehansen, Uccle, Belgium Application October 25, 1934, Serial No, 750,008

In France October 31, 1933 10 Claims. (01. 204-21) The present invention comprises processes and electrolytic cells for the production of alkali metals and alkaline-earth metals, especially metallic sodium, by electrolysis of fused alkali metal compounds such as sodium nitrate or sodium hydroxide' or the corresponding compounds of potassium or lithium.

Processes. are known, such' as the Darling procproduce metallic sodium and nitric acid. None of the known processes, however, afiords any means of preventing the migration of the nitrate ion (N03) from the anode chamber to the cathode chamber, where it reforms sodium nitrate by reaction with the-metallic sodium liberated at the cathode; neither does any one of the known processes provide for neutralizing the detrimental effects of this migration.

There are also known processes for the electrolysis of caustic soda, but in these the current efiiciency does not exceed about 50% owing to a secondary reaction between the liberated bydroiwl ions whereby water and oxygen are formed.

According to the present invention these defects are remedied by carrying out the electrolysis of the fused compound; for example the 111- trate or the hydroxide, in the presence of an auxiliary salt of the same metal, such salt being able through a secondary chemical reaction, to

fix the anodic products formed during electrolysis, for example the nitrate ion or the-hydroxyl ion, and to reform the salt undergoing electroly- 'the presence of sodamide is advantageous in that the melting point of the electrolytic bath' is thus very' much lowered and the secondary reaction between sodium and water at the cathode with formation of hydrogen is suppressed and thus all -quently absolutely pure.

The process of electrolysing caustic soda in danger-of explosion is avoided. The consumption of current necessary to maintain the bath in a, state of fusion is reduced and. the number of lnlowatt-hours consumed for each kilogram of sodium produced in the metallic state is correspondingly reduced.

-The use of sodamide in the electrolyte causes at the cathode an evolution of gas twice as great as that obtained in the electrolysis of caustic soda alone. This increase in volume of the evolved gas favours the elimination as water vapour of part of the water'formed during electrolysis, and since water so eliminated does not react with the sodamide the quantity of the latter required for fixation of water is thus minimised.

The caustic soda formed by hydrolysis of the sodamide remains in the electrolyte. This formation takes place in the anode compartment, which is advantageous in the case of the electrolytic operation.

For each kilogram of sodium produced it is necessary to sacrifice nearly half a kilogram to reform the amide outside the electrolytic 'cell by reaction with the liberated ammonia after having taken care to separate the oxygen and moisture from the ammonia, which presents no difficulty. The oxygen may be sold separately and the manufacture of sodamide may be carried out easily by well known means. A result of the suppression of the water-formation at the anode is to more than double the current ,eificiency. This advantage is, however, in part lost because of the necessity of constantly reforming the amide.

Nevertheless the suppression of the danger of explosion permits the construction of totally enclosed large units with perfect safety.

Lastly, nearly half of the causti 'r soda 'to be treated is produced from sodamide and is conse- Loss of caustic soda through resolution and washing in the cleaning of the plant is reduced to a minimum, since the cells may be operated for long periodswithout interruption.

According to another embodiment of the'invention fused sodium nitrate is electrolysed in the presence of sodium carbonate which is able to fix the oxides of nitrogen liberated at the anode by the electrolysis of the said nitrate, giving in exthe sodium nitrate. This anodic'secondary-reaction maybe written:

The result of the electrolysis is thus the decomchange carbon dioxide gas which is inert toward Position of the nitrate with reformation of this nitrate through the-action of the nitrogen prod- The principal product to be added is calcined sodium carbonate, NazCOa (or bicarbonate) in .quantities corresponding to the' above chemical reaction. As in the case of electrolysis of caustic soda described above any formation of water which might reduce the current efiiciency is avoided and the migration of nitrate ions toward the cathode is prevented. The production of by products of little valueand difiicult to dispose of, like chlorine, is avoided and those actually obtained, viz., carbon dioxide and oxygen, may even be discharged into the open air without inconvenience, though their sale is generally a source .of supplementary profit. The number of kilowatthours required for the production of akilogram of sodium may be considerably reduced. Such an electrolytic installation may profitably be associated with a factory producing sodium carbonate by the ammonia-soda process. 1

According to this invention sodamide may also beadded to the cathode compartment and this further reduces the melting point of the bath,

already lowered by the presence ofvnitrate and nitrite of sodlunr'in the anode compartment.

The sodium nitrite is formed by electrolytic reduction and has a melting point 30 lower thanthe nitrate, while the amide melts at 100 lower than the nitrate which again melts 15 below the melting point of caustic soda. The amide has the further advantage of preventing any migration of nitrate ions toward the metallic sodium produced at the cathode since it fixes this gas with formation of free or combined ammonia.

According to another embodiment of this invention the electrolysis of sodium nitrate is carried out so as to utilise natural sodium nitrate (Chile ,saltpeter) as the raw material. 'For this purpose the cathode chamber is charged with fused sodamide, mixed preferably with a fused neutral body, a. good electrical, conductor, preferably of, a density less than that of. metallic sodium and having a high boiling 'point about or above 250 0. Such bodies are especially, various parafiins and organic products such as naphthoquinoline, dambose, (CsHuOe), chrysene,-cholesterin, carbazol-, anthrapurpurin, acridon, phenanthraquinone, brasane, (CcHuOs), anthracene, anthraquinone, succinamide, tetraoxybenzene, diphenyl and derivatives thereof, oildag (colloidal solution of graphite in parafiln) parafllns such as ozokerite or ceresine and other analogous products, rendered electrically conducting by colloidal solution therein of sodamide, graphite or analogous substances.

According to one feature of this invention there are used between the anode and cathode compartments double diaphragms, hereinafter referred to as chemical diaphragms, consisting of two ordinary diaphragms containing betweenthem a layer or wall of solid sodium carbonate, which prevents the migration of the nitrate ions toward the cathode.

Other characteristic features and details of the present invention will be apparent from the description of the drawings attached to this specification which represent'in outline various elect olyticcells which are part of this invention and are used for carrying out the processes herein described. These examples refer especially to the electrolysis of salts of sodium, potassium or lithium.

Figure 1 is a vertical section of a cell according to the present invention.

Fig. 2is a plan view of the cell shown in Fig. 1.

Fig. 3 is a. view similar to Fig. 1 showing a modification of the present invention.

Fig. 4 is another view similar to Fig. 1 showing a further modification.

Fig.5 is a perspective view of an electrode according to the present invention.

Fig. .6 is a vertical section of a modified cell.

Fig. 7 is a ver'ticalsection of a further modified form of cell.

Fig. 8 is a vertical section of a still further modified form of cell. 7 a Fig. 9 is a vertical section of yet another modified form of cell.

In Figs. 1 and 2 the cell has anodes 2 prefer ably of nickel, and cathodes 3. of nickel or coppertin alloy. The separating of the anodlc and cathodic products is effected by means of a diaphragm 4, either metallic and insulated, or'made of asbestos, porous cement, magnesia or other relatively insulating material which may be tratromotive force.

According to one form of theinvention the solid part of the diaphragm is constructed of titanium dioxide in powder, with or without the addition of asbestos, magnesia or analogous products together with a pasty product to form a porous cement. The cell contains as electrolyte fused sodium hydroxide and sodamide in'equivalent proportions (i. e. with regard to sodium content). Preferably it contains also calcined sodium carbonate in variable proportions between 12% and 20%. The oxygen and ammonia, liberated as gases, escape through the tube 0 which may also serve as safety valve. y

The metallic sodium formed by the electrolysis at the cathode may be withdrawn either at the upper or at the lower part 1 of the cell, depend ing on the density of the electrolyte relative to the density of sodium, and the density of the electrolyte. may be controlled by varyingthe proportions of its constituents. The raw materials, 1. e. the caustic soda and sodamide, may be introduced into the cell through a funnel 8 placed in the upper part above the level of the electrolyte in such a way as to cause a trickling of these fused salts, preferably on the anode side of the diaphragm. These funnels which extend well below the level of the electrolyte, carry an arrangement forheating, preferably electrical, which may be regulated at will so as to obtain a progressive fusion of the salts, for the purpose of maintaining the trickling mentioned above and at the same time securing, by means of the funnels, hermetic closure of the cell. The corresponding-elements are designated in Figs. 1 and 2 by the samereference numbers. The cell shown in Figs. 1

and 2 may equallywell be employed to elec- I versed by the ions under the influence of an electrolyse. a mixture of. sodium nitrate and sodium carbonate in equivalent proportions. The sodium nitrate is decomposed-by electrolysis liberating sodium at the cathode and nitrogen products at the anode. The development of nitrogen prod ucts fat the anode is followed by a secondary chemical reaction with formation of carbon dioxide (which may either be released into the air or may be recovered) and with re-formation of the quantity of nitrate originally decomposed.

an electrolysis is thus particularly adapted to be associated with a works producing sodium carbonate. Preferably sodamide is added in the cathode compartment to lower the melting point of the mixture and to protect the sodium from, the nitrogen oxides.

In the cell represented-by Fig. 3 are cathodes l2, and anode i3 and diaphragms 14, which are so-called chemical diaphragms consisting of two ordinary diaphragms l5 and it between which is a layer or wall of sodium carbonate. The anodes and cathodes are preferably made of-aluminiumor nickel. According to one feature of the invention electrodes (cathode and/or anode) are employed in the form of a metallic netting which facilitates the operation by permitting an easier renewal of the electrolyte around the electrodes. The cathoylte is sodamide: the anolyte is sodium nitrate. Preferably there is added'to the catholyte a neutral fused product such as a paraflin rendered electrically conducting, either by the sodamide or by another substance such as graphite, in colloidal solution. This paraflin is preferably of less specific gravity than soproducing carbon carbon dioxide,

dium and such that the boiling pointis above 250 C.

In the example ments are placed between the cathode compartments. Thus it is easy to maintain inthe exterior cathode compartments a temperature slightly below that in the anode compartments with a minimum loss of heat and under the best conditions for the two different operations involved in the two compartments, namely the electrolysis and the secondary reaction respectively. All these products in a fused state are exposed to electrolysis. The decomposition of the sodium nitrate with liberation of metallic sodium at the cathode and formation of nitrate ions (NOa-) is followed by a secondary reaction whereby the nitrogenous. products which penetrate into the chemical diaphragm II decompose the sodium carbonate therein contained dioxide gas and forming nitrate and nitrite of sodium.

The chemical diaphragm is preferably constructed on the cathode side of an asbestos sheet armed with metallic netting IE or of a mixture of asbestos fibres and magnesia powder. The sheet is rendered resistant to the attack of nitrous gases which might penetrate so far by migration, through its impregnation by the salts or paraflins contained in the catholyte. Alternatively, a sheet made of cement based outitanium dioxide might be employed.

Owing to the presence of the chemical diaphragm any migration of the nitrogenous products to the metallic sodium at the cathode is prevented. The metallic sodium produced may be withdrawn at the upper part of the cell if lighter than the electrolyte or at the lower part of the cell if heavier than the electrolyte. The gaseous products, consisting of oxides of nitrogen and/or possibly with an admixture of oxygen are drawn off at the outlet l1 and transformed to nitric acid by washing and absorption in water.

The raw materials consist primarily of sodium 7 nitrate and secondarily of sodium carbonate, the

latter being required in quantity corresponding shown the anode compart- -or conduits may be cylinder closed at the to the extent to which the nitrate is formed from it owing 'to the migration ofv nitrate ions. The

sodium nitrate is introduced into the anolyte as' controlled owing to the visibility of the level oftheproducts in the funnel.

According to another form of construction of cell represented in Fig. 4 the cathode 22 is opposite to and above the anode 2. The cathode chamber contains an interior insulated ring 22a and also another ring or annulus 22b which carries a metallic net 220 constituting the cathode proper. A diaphragm ring 23 carries a diaphragm 23a composed of an asbestos sheet or the like fixed between two metallic nets. anode 24 comprises a metallic sheet Ila carrying a metallic net has the anode proper. These two metallic nettings 22c and 24b form the effective electrodes, with the advantage that they permit the free passage of the electrolyte products and facilitate the instantaneous renewal of the decomposed electrolyte by fresh layers of the fused salts. In the cathode compartment the electrolyte is fused sodamide, preferably mixed with a paraflin orone of the analogous products named above. In the anode compartment the electrolyte consists principally of sodium nitrate.

According to another form of this invention the electrodes employed (anodes and cathodes) have the form of troughs of V-section. Two such electrodes, which may replace the cathode and anodeof Fig. 4, are indicated in Fig. 5. They are placed as shown, the cathode 2 2' within the anode 24' and between them is placed the. diaphragm-(not shown in Fig. 5) analogousto the diaphragm 23a of. Fig. 4.

The included angle of the troughs is generally between 30 and and the troughs are slightly inclined to the horizontal. Contrary to what occurs'in the electrolysis of sodium chloride the operation of such electrodes is made advanta-' geous without any practical difficulty. This is due to the relatively low working temperature and to the manner in which the form of these electrodes facilitates the escape of the anodic gases and hinders their penetrating into the cathode chamber or even adhering to the diaphragm. The heavier products flow downwards and the lighter products rise, which facilitates their separation and their continuous or periodic withdrawal, automatically or otherwise.

-When, as shown, the cathode is placed within the anode, the liberated dropsof sodium which aggregate within the cathode will rise or fall in the cathodic trough according as their density is less or greater than that of the electrolyte. In case a. layer of anodic products gathers in the cathodic trough above the fused salts by infiltration through the diaphragm, this layer may be evacuated from the corresponding part of the said trough if it is hindering the work of the cell. Alternatively, the V-shaped troughs turned upside down.

Figure 6 represents yet another form of electrolytic cell according to this invention. V

The cathode 32 is placed within a diaphragm 33 composed of metallic netting (preferably of aluminum or nickel) which has the form of a lower end-and insulated from the cathode 32. The anode it is also made preferably of aluminium, nickel or bronze. In the cathode compartment 32h the electrolyte 7 consists of a mixture of sodamide with paraiiin,

which is thus made conducting, or of one of the analogous bodies mentioned above. In the anode compartment 341:. the electrolyte consists of canstic soda. and sodamide. With the construction here adopted, the metallic sodium produced at the cathode may advantageously be removed through the lower part of the hollow cathode 32 subject, naturally, to the adjustment of the composition of the catholyte so that-it is less dense than sodium.

Alternatively the sodium maybe skimmed from the uppenpart of the cathode chamber 32h either by an automatic overflow or by hand, if the density of the catholyte exceeds that of sodium.

Figure '7 shows a form of construction having a cathode 42, an anode '44, placed within' the cathode chamber and outflow pipes 48a and 48b.

The outlet for gaseous products is shown at 49.

As before, the catholyte is sodamide mixed with a parafiin or analogous product, while the anolyte consists of sodium nitrate or Chile saltpetre. The diaphragm 43 is constructed, as in the case of Fig. 5, by means of a metallic net, an asbestos sheet impregnated with calcined magnesia, titanium oxide or the like.

In the form of construction shown in Fig. 8 the cell comprises a cathode 52, a diaphragm 53 and an anode 54. The catholyte is the same as that specified in. relation to Figs. and 6. This electrolyte is renewed as required through the funnel 55; -The. composition of the catholyte is regulated so that its density is greater than that of sodium which, therefore, is readily withdrawn by a syphon arrangement as represented, the electrolyte carried ofi with the metal being recovered in the vessel 56 where the metallic sodium will float on top.

Fig. 9 represent a cell analogous to that shown in Fig. 3, embracing the'cathodes B2, anodes 63 and chemical diaphragms 64. It is further provided with arrangements for the introduction of raw material (not shown) and an outlet pipe 65 for gaseous products. The cellalso has apipe 66 which can rotate about the axis of the connector B'I-and serves for the automatic removalof the alkaline metal produced. When the electrolyte is less dense than the sodium the pipe 66 is attached to the lower part of the cell. I If, however, the sodium is the less dense, the pipe 66 is attached to the upper part of the cell. The pipe 66 serves also as a compensator for the difierence of pressure between the cathodic and anodic' compartments, the pressure being generally greater in the anodic compartment because it contains the heavier products.

It happens frequently that the anodic compounds penetrate more or less slowly into thecathode compartment, whence they may be with-- drawn periodically by means of the orifice 68. To facilitate such withdrawal the bottom of the cell is preferably inclined toward this orifice and may, further, be provided with inclined grooves for the same purpose. As the pipe 65 is movable around the connection 61 it may, it put in the position shown by the dottedlines, serve to empty the cell.

It is evident that the invention is not exclusively limited to the particular embodiments thereof represented or described above and that several modifications may be introduced in the form, the number and the disposition of the elements concerned in its realisation without thereby going outside the scope of this invention.

nitrate is eifected with a chemical ently in the various electrolytic cells by means of appropriate modifications in those cells. The process for electrolysing caustic soda, the process for electrolysing a mixture of sodium nitrate and carbonate with consumption of the carbonate and the process in which the electrolysis of sodium ing sodamide in the cathode compartment and consuming sodium nitrate, may all be effected in one or other of the-said cells. Equally, in stead of electrolysing sodium salts, one may electrolyse' other alkali metal salts, e. g. those of potassium lithium, rubidium or cesium, or salts of the alkaline earth metals, beryllium, magnesium, calcium, strontium, and barium.

Finally, in the case of utilising the chloride and sulphate of sodium as raw materials, it is advantageous, in order to lower the working temperature, to carry out the electrolyses in the presence of sodium nitrate. At any rate, there diaphragm usand an auxiliary consumption of chloride or sulphate and of carbonate and/or amide of sodium according to the nature of the auxiliary salts of sodium employed in addition to the principal salt, sodium nitrate.

Generally, in practice, the anode and cathode on either side of the diaphragm are brought as close together as possible in order to reduce to a minimum the voltage required to drive the required current through the electrolyte. This distance is, in fact, considerably less than that shown in the figures appended thereto, without otherwise afiecting the principles of the constructions illustrated.

When the cathode compartments are arranged on the outside of the anode compartments the outer cathode compartments may be provided on the exterior side with tubes or double walls through which is circulated a neutral liquid such as paraflln, diphenyl or the like, ata temperature of about 200 0., this liquid being maintained at the desired temperature by means of heating or cooling in a central reservoir outside the cells which can be connected at will with any or all of the cells by a system of pipes provided with stopcocks to each cell whereby the fiow'of liquid and consequently the heat supplied to or abstracted from each cell can be regulated. Thus it is possible to secure a constant temperature suitable for the electrolysis and so to keep this temperature at the lowest practicable point, which favours the efliciency of the process. The temperature of the electrolyte may also be held-constant by means of thermostats controlling either the flow of the liquid to the double walls or the supply v the presence 01' auxiliary salts which intervene amasse ,5.

in secondary chemical reactions. Even when the cathode compartments are placed within the anode compartments it is still possible to utilize an arrangement of the type here described for p controlling the temperature in these compartments.

The term carbonates recited in the claims is '20 of said cell and a catholyte of a fused auxiliary compound selected from the group consisting of amides and carbonates of the alkali metal to be produced in the cathodic compartment, and passing a direct electric current between said elec- 25 trodes to electrolyze said anolyte forming the alkali metal to be produced at the cathode and causing anodic products accidentally entering the cathodic compartment to react with the catholyte to regenerate the anolyte with simultaneous lib- 30 eration of a gas formed from said auxiliary compound.

2. A method for the electrolytic production of alkali metals in an electrolytic cell having two electrodes, the cathode being of a metal other 35 than the metal which is to be obtained, and a diaphragm separating the cell into anodic and cathodic compartments, comprising introducing a fused hydrate of the metal to be produced in the anodic compartment and a fused amide of the 4o same metal in the cathodic compartment, and

' passing a direct electric current between said.

electrodes to electrolyze the anolyte forming the alkali metal to be produced at the cathode and causing the hydroxyl ions resulting from the 45 hydrate to react with the amide to reform the hydrate of said metal and liberate ammonia.

3. Amethod for the electrolytic production of alkali metals in an electrolytic cell having two electrodes, the cathode being of. a metal other 5 than the metal which is to be obtained, and a diaphragm separating the cell into. anodic and cathodic compartments, comprising introducing a fused nitrate of the metal to be produced in the anodic compartment and a fuse amide of the' 55 same metal in the cathodic compartment, and

passing a. direct electric current between said electr'odesto electrolyze the anolyte forming the alkali metal to be produced at the cathode and causing the nitrate ions resulting from the ni-" trate to react with the amide to reform'the nitrate -of said metal and liberate ammonia. 4. A method for the electrolytic productionof alkali metals in an electrlytic cell having two electrodes, the cathode being of a metal other than the metal which is to be obtained, and a diaphragm separating the cell into anodic and cathodic compartments, comprising introducing a fused nitrate of the metal to be produced in the anodic compartment and a fused carbonate of the same metal in the cathodic compartment, and

passing a direct electric current between saideleotrodes to electrolyze; the anolyte forming the alkali metal to be produced at the cathode and causing the nitrate ions resulting from the nitrate to react with the carbonate to reform the nitrate of said metal and liberate carbon dioxide,

5. A method for the electrolytic production of alkalimetals in an electrolytic cell having two electrodes, the cathode being of a. metal other than the metal which is to be obtained, and a diaphragm containing a carbonate of the metal to be obtained separating the cell into anodic and cathodic compartments, comprising introducing a fused hydrate of the metal to be produced in J the anodic compartment and a fused amide of the same metal in the cathodic compartment, and passing a direct electric current between said electrodes to electrolyze the anolyte forming the alkali metal'to be produced at the cathode and causing .the hydroxyl ions resulting from the hydrate to react with the amide to reform'the hydrate of said metal and-liberate ammonia.

, 6. A method for the electrolytic production of alkali metals in an electrolytic cell having two electrodes, the cathode being of a metal other than the metal which is to be obtained, and a diaphragm containing a carbonate of the metal to be obtained separating the cell into anodic and cathodic compartments, comprising introducing a fused nitrate of the metal to be produced in the anodic compartment and. a fused amide 5 of the same metal in the cathodic compartment,

and passing a direct electric current between said electrodes to electrolyze the anolyte forming the alkali metal to be produced at the cathode and causing the nitrate ions resulting from the nitrate to react with the amide to reform the nitrate'of said metal and liberate ammonia.

'7.-A method for the electrolytic production of 5 V alkali metals inan electrolytic cell having two electrodes, the cathode being of a metal other than the metal which is to be obtained, and a diaphragm separating the cell into anodic and cathodic compartments, comprising introducing 4o an anolyte of a fused compound of the alkali metal to be produced in the anodic compartment of said cell and an amide of said metal together with paraffin having graphite dispersed therein in the colloidal state in the cathodic compartment,

and passing a direct electric current between the electrodes to electrolyze the compound in the anodic compartment formingthe alkali metal to be produced at the cathode and causing the anodic products accidentally entering the cath- 5 odic compartment to react with'the amide to re form the compound of said metal introduced in the anodic compartment and to liberate ammonia.

8. A method for the electrolytic production or I alkali metals in an electrolytic cell having two electrodes, the cathode being of a metal other than the metal which is to be obtaine'd and a diaphragm separating the-cell into anodic and cathodic compartments, comprising introducing an anolyte of a fused compound of the'alkali metal to be produced in the anodic. compartment of said cell alongside of the diaphragm and a catholyte of a fused auxiliary compound selected from the group consisting of amides and carbonates of the alkali metal to be produceddn the cathodic compartment alongside ofthe diaphragin, passing a direct electric current between said electrodes to electrolyze said anolyte forming the alkali metal to be produced at the cathode and causing anodic products accidentally entering the-cathodic compartment to react with the catholyte to regenerate the anolyte with'simultaneous liberation of aga formed from said 7 auxiliary compound, and regulating the temperature of the material introduced into said' cell. 7

9. A- method for the electrolytic production or alkali metals in an electrolytic cell having two electrodes, the cathode being of a metal other than the metal which is to be obtained, and a diaphragm containing titanium dioxide separating the cell into anodic and cathodic compartments, comprising introducing an anolyte 01 a fused compound 01' the alkali metal to be produced in the anodic compartmentpf said cell and a catholyte of a fused auxiliary compound selected from the group consisting of amides and carbonates of the alkali metal to be produced in the cathodic compartment, and passing a direct electric current between said electrodes to electrolyze said anolyte forming the alkali metal to be produced at the cathode and causing anodic products accidentally entering. the cathodic compartment to react with the catholyte to regenerate theanolyte with simultaneous liberation of a gas formed from said auxiliary compound.

10. A method for the electrolytic production or alkali metals in an electrolytic cell having two electrodes; the cathode being of a metal other than the metal which is to be obtained, 9. diaphragm separating the cell into a cathodic compartment, and an anodic compartment in the middle or the cathodic compartment, comprising introducing an anolyte of a fused compound of the alkali metal to-be produced in the anodic compartment of said cell and a catholyte of a fused auxiliary compound selected from the group consisting of amides and carbonates oi. the alkali metal to be produced in the cathodic compartment, and passing a direct electric current between said electrodes to electrolyze said anolyte I forming the alkali metal to be produced at the cathode and causing anodic products accidentallyentering the cathodic compartment to react with the catholyte to regenerate the anolyte 'with simultaneous liberation of a gas formed from said auxiliary compound.

IVAR JUEL MOL'I'KEHANSEN. 

